Plastic battery case



Jan. 25 1955 H. A. GOTTSCHALL 2700695 PLASTIC BATTERY CASE Filed Des.10, 1953 POLYMONOGH LOROFLUOROETHYLENE STRIP 2 POLYSTYRENE CYLINDER lPOLY MONOGHLOROFLUOROETHYLENE TUE! N G 3 INNER STRIP 2 OUTER STRIP 4POLYSTYRENE CYLINDER l INVENTOR. HERBERT A. GOTTSCHALL United StatesPatent O PLASTIC BA'ITERY CASE Herbert A. Gottschall, Clifton, N. J.assignor to the United States of Amerlca as represented by the Seeretaryof the Army Application December 10, 1953, Serial N0. 397,497

5 Claims. (C1. 136-166) (Granted under Title 35, U. S. Code (1952), sec.266) This invention relates to improved plastic battery cases and cellcontainers.

Plastic battery ca-ses and cell oontainers made from various synthetichigh polymers such as polystyrene, polyethylene, polyvinyl chloride,polyvinylidene chlor1de, or polymonochlorofluoroethylene or the like arewell known in the art but their use has in the past bcen limited due tothe relatively high vapor permeabllity cf low cost ple ts tics such aspolystyrene or due to the high costs of plastxcs of relatively low vaporpenneability such as polymonochlorofluoroethylene or the like.

lt is an objeet of the invention to reduce the vapor permeability ofplastic battery cascs and cell contain ers without substantiallycomplicating the manufacturmg process and without considerablyincrea-sing the cost of the new battery case er cell container.

These and other objects of the invention will be aehieved by the batterycase aceording to the invention which cousists of a dual wall of plasticmaterials. One cf the walls of the new battery case comprises a thickerwall cf a syn thetic high polymer of relatively high vapor permeabilityand relatively low cost while the thinner wall comprises a synthetichigh polymer of relatively low vapor permeability though of relativelyhigher eosts.

The invention will become more apparent from the following descriptioncf specific embodiments of the broad inventive idea as illustrated inthe three figures of the -accompanyiug drawing.

Fig. 1 shows in cross-section a cylinder 1 made from polystyrene er anyother known modified polystyrcne as used in the manufacture of cellcases and cut t0 the desired length of the battery case.Polymonochlorofluoroethylene sheeting 15 mils thick is then cut tostrips 2 of a width corresponding to the height of the polystyrenecylinders, e. g., 0.55 lach. The strips of polymonochlorofiuoroethyleueare then cut to such a length that when the strips are laid upon theinside surface of the polystyrene cylinders the strips overlap by aboutA; cf an inch. The overlap is now sealed with a cement (not shown in thedrawing) made by dissolving polyvinylidene chloride in an appropriatesolvent such as methyl ethyl ketone. The dual wall container is thenallowed to dry for about 12 to 24 hours before beiug used to assemble acell.

Other combiuations of plastic materials cf relatively low and relativelyhigh vapor permeability are for instance: polyethylene liuers withpolystyrene, polyvinylidene chloride liners with polystyrene,polymonochlorofluoroethylene liners with polyvinyl chloride, polyvinylchloride liners with polystyrene, etc.

In the specific embodiment cf Fig. 2 polystyrcne cylinders 1 of 0.498inches inner diameter and 0.625 inches outer diameter were machined onthe inside so that a p01ymonochlorofluoroethylene tubing 3 (cf 0.500inches immer d-iameter and a wall thickness of 0.012 inches) could justbe slippe"d inside the polystyrene cylinders. The assembled doublecylinders were then immediately used for the manufacture of cell cases.

The plastic material of low vapor transmission can be positioned 011 theoutside or the inside of the cylinder of high vapor transmission. Insome cases it is advantageous to use 3 or more layers, as illustrated inFig. 3 by making a cylinder 1 of plastic material of low vaportransmission the middle layer of a sandwich wall in which both the immerlayer 2 and the outer layer 4 oonsist 0f plastic material of high vaporpermeability.

Battery containers or cell containers aecording to the inventlon may bemade commerc-ially by multiple extrusion. The process of multipleextrusion and extruders tpable of performing this operation are wellknown in e art.

Multiple wall cylinders according to the preseut invention are mostsuitable where a very thin layer of a comparatlvely expensive materialof very low vapor transmission is used in combination with a lessexpenslve material of a comparatively high vapor transmiss1on.

It will be apparent to those skilled in the art that various changes ormodifications of the disclosed embodiments may be made without departingfrom the inventive idea as characterized in the appended claims.

The invention described in the foregoing specification and claims may bemanufactured and used by or for the Government for governmentalpurposes, without the payment to me of any royalty thereou.

What is claimed is:

l. Battery case and cell container consisting -of a dual Wall cf plasticmaterial eomprising a thicker wall of a synthetic high polymer cfrelatively high vapor perrneability and a thinner wall of a synthetichigh polymer of relatively low vapor permeability.

2. Battery case and cell eont-ainer according to claim 1 in which thethicker wall eonsists of p-olystyrene and the thinner wall of a memberselected from the group C011- sisting of polymonochlorofluoroethylene,polyvinylidene chloride, polyethyleue and polyvinyl chloride.

3. Battery case and cell container according to claim 1 in which thethicker wall eonsists of polyvinyl chloride and the thinner wall ofpolymonochlorofluoroethylene.

4. Battery case and cell container comprising a thicker wall of asynthetic high polymer of relatively high vapor permcability sandwichedbetween thinner Walls cf a synthetic high polymer cf relatively lowvapor permeability.

5. Battery case and cell container comprising a cylinder of polystyrenelined with a thin film of polymonochlorofluoroethylene.

Refereuces Cited in the file of this patent UNITED STATES PATENTS MowryMax. 18, 1947 Ditz Dec. 11, 1951

1. BATTERY CASE AND CELL CONTAINER CONSISTING OF A DUAL WALL OF PLASTICMATERIAL COMPRISING A THICKER WALL OF A SYNTHETIC HIGH POLYMER OFRELATIVELY HIGH VAPOR PERMEABILITY AND A THINNER WALL OF A SYNTHETICHIGH POLYMER OF RELATIVELY LOW VAPOR PERMEABILITY.